/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.runners.core.construction;



import com.bff.gaia.unified.sdk.util.ZipFiles;

import com.bff.gaia.unified.vendor.guava.com.google.common.base.Strings;

import com.bff.gaia.unified.vendor.guava.com.google.common.hash.Funnels;

import com.bff.gaia.unified.vendor.guava.com.google.common.hash.Hasher;

import com.bff.gaia.unified.vendor.guava.com.google.common.hash.Hashing;



import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.net.URISyntaxException;

import java.net.URL;

import java.net.URLClassLoader;

import java.util.ArrayList;

import java.util.List;

import java.util.stream.Collectors;



import static com.bff.gaia.unified.vendor.guava.com.google.common.base.Preconditions.checkArgument;



/** Utilities for working with classpath resources for pipelines. */

public class PipelineResources {



  /**

   * Attempts to detect all the resources the class loader has access to. This does not recurse to

   * class loader parents stopping it from pulling in resources from the system class loader.

   *

   * @param classLoader The URLClassLoader to use to detect resources to stage.

   * @throws IllegalArgumentException If either the class loader is not a URLClassLoader or one of

   *     the resources the class loader exposes is not a file resource.

   * @return A list of absolute paths to the resources the class loader uses.

   */

  public static List<String> detectClassPathResourcesToStage(ClassLoader classLoader) {

    if (!(classLoader instanceof URLClassLoader)) {

      String message =

          String.format(

              "Unable to use ClassLoader to detect classpath elements. "

                  + "Current ClassLoader is %s, only URLClassLoaders are supported.",

              classLoader);

      throw new IllegalArgumentException(message);

    }



    List<String> files = new ArrayList<>();

    for (URL url : ((URLClassLoader) classLoader).getURLs()) {

      try {

        files.add(new File(url.toURI()).getAbsolutePath());

      } catch (IllegalArgumentException | URISyntaxException e) {

        String message = String.format("Unable to convert url (%s) to file.", url);

        throw new IllegalArgumentException(message, e);

      }

    }

    return files;

  }



  /**

   * Goes through the list of files that need to be staged on runner. Removes nonexistent

   * directories and packages existing ones. This is necessary for runners that require filesToStage

   * to be jars only.

   *

   * @param resourcesToStage list of resources that need to be staged

   * @param tmpJarLocation temporary directory to store the jars

   * @return A list of absolute paths to resources (jar files)

   */

  public static List<String> prepareFilesForStaging(

      List<String> resourcesToStage, String tmpJarLocation) {

    return resourcesToStage.stream()

        .map(File::new)

        .filter(File::exists)

        .map(

            file ->

                file.isDirectory()

                    ? packageDirectoriesToStage(file, tmpJarLocation)

                    : file.getAbsolutePath())

        .collect(Collectors.toList());

  }



  private static String packageDirectoriesToStage(File directoryToStage, String tmpJarLocation) {

    String hash = calculateDirectoryContentHash(directoryToStage);

    String pathForJar = getUniqueJarPath(hash, tmpJarLocation);

    zipDirectory(directoryToStage, pathForJar);

    return pathForJar;

  }



  private static String calculateDirectoryContentHash(File directoryToStage) {

    Hasher hasher = Hashing.sha256().newHasher();

    try (OutputStream hashStream = Funnels.asOutputStream(hasher)) {

      ZipFiles.zipDirectory(directoryToStage, hashStream);

      return hasher.hash().toString();

    } catch (IOException e) {

      throw new RuntimeException(e);

    }

  }



  private static String getUniqueJarPath(String contentHash, String tmpJarLocation) {

    checkArgument(

        !Strings.isNullOrEmpty(tmpJarLocation),

        "Please provide temporary location for storing the jar files.");



    return String.format("%s%s%s.jar", tmpJarLocation, File.separator, contentHash);

  }



  private static void zipDirectory(File directoryToStage, String uniqueDirectoryPath) {

    try {

      ZipFiles.zipDirectory(directoryToStage, new FileOutputStream(uniqueDirectoryPath));

    } catch (IOException e) {

      throw new RuntimeException(e);

    }

  }

}